LONG POND, Pa. -- It bit Greg Biffle for the first time at Las Vegas, where the No. 16 car twice led the race but eventually faded to 28th. It bit Tony Stewart last weekend in Kansas City, where the No. 14 car was in contention for the victory before it wound up eighth. They were two strong runs separated by three months but both derailed by the same, elementary reason -- they weren't able to get their vehicles fully fueled on pit stops, and their drivers ran prematurely dry as a result.

Fuel mileage has dominated NASCAR in recent weeks, with Sprint Cup events at Charlotte and Kansas and a Nationwide Series race at Chicagoland all being decided by how much drivers had left in the tank. It's all placed a natural focus on those on-the-fly calculations that team engineers make to try to divine how far their cars can go until the fuel cells run dry. And yet, as NASCAR comes to a Pocono Raceway with a history of producing gas-mileage outcomes, crews are also dealing with another hurdle that could factor into the finish -- the seemingly simple chore of filling the tank.

“The pit crews have gotten so good ... that they can get the tires on the race car faster than you can get the car full of gas.”-- GREG BIFFLEIt's not so simple anymore. Spurred in part by the move to an ethanol blend of fuel, this past offseason the Cup tour switched to a new fueling system that fuels and vents in one process, and eliminates the need for a catch-can man. The new can has been used in the Camping World Truck Series, but some Cup operations have struggled to adapt. The current, longer-necked can seems to require a greater degree of precision on the part of the fuel man, and it unquestionably takes longer to empty, factors that can lead to a splash of gas being spilled on the pit-box concrete or not all 12 gallons flowing into the tank.

And it doesn't take much spilled or unused fuel to make a difference in an end-of-race scenario like those that have unfolded so many times in recent weeks, with teams trying to stretch their fuel runs beyond their usual windows and all the way to the finish. Biffle, who unfortunately has as much experience with the issue as anyone else in the garage area, believes refueling misadventures are having an impact on race outcomes.

"Absolutely. One-hundred percent," he said. "The issue is that the teams are faster than you can fill the car with gas. It is that simple. The pit crews have gotten so good, and the guys have gotten so good and trained and worked so hard, that they can get the tires on the race car faster than you can get the car full of gas. Congrats to them for how hard they have worked and what they have accomplished. With the new fuel connection or whatever you want to call it, has slowed up the fueling of the car enough to where you can literally change tires faster than you can fuel. Not by much, but it doesn't take much. When you are filling 18 gallons in 12 seconds, 1 second, you do the math on how much fuel that is. It is over a gallon a second."

Leaving the pit box without that final gallon can make a huge difference at a place like 2.5-mile Pocono, where Stewart won on fuel mileage two years ago. Avoiding that issue, Biffle said, requires an almost direct hit on the part of the fuel man, as well as patience on the part of the driver to stay in the box until the entire fuel load is transferred. Drivers are accustomed to speeding out of the pit box as soon as the jack drops; now, with fuel cans that take longer to fill the car, they're often held by crew chiefs for those few extra seconds it takes for the fuel man to do his job.

"Sometimes you have to wait, and that last little bit of fuel can impact a race hugely," Carl Edwards said. "If you look at our Nationwide race at Chicago, [the car] was full, but that was a race that showed you that six more ounces of fuel and you can win the race or be the difference between winning or losing. The gas man is a bigger part now than I think they were before. It is hard to wait on pit road. It is hard for everybody."

For drivers who have avoided the problem, the biggest change is the longer wait on a pit stop. "Having to wait just a little bit longer is the biggest thing that I've noticed," Clint Bowyer said. " You see your tires guys done, [hear] no more impact [wrenches] zinging, and you're still up on the jack and you're like, what's going on? You think maybe one of them hung a lug nut or something, then all of a sudden it comes down and you realized it was the gas that you were waiting on. Had that a couple of times. As far as getting it to the end and actually getting the fuel in the car, I think that just happens to be the talent or whatever putting it in there."

There are all kinds of variables -- crew chiefs taking two tires, the way the fuel settles in the car while it's up on the jack, the way those last few gallons seem to take their time gurgling-gurgling in, the fuel man making a perfect seal between the can's neck and the car's fuel opening. "You've got to be real precise in how you get it connected," Jeff Gordon said. And the driver has to be real patient, understanding that the track position he's giving up by waiting longer on pit road will translate into more gas in the tank -- and potentially, a better finish if the event comes down to fumes.

"I think that's what we're looking at now is, it's more important to get the fuel in there than it is to have that 13-second stop when it's coming down to the end of the race," Gordon said. "And so I think that's where I give [crew chief] Alan [Gustafson] a lot of credit for really focusing on those areas to make sure that we do everything we can. When we're there for that stop, we do everything we can to get all the fuel in it. I feel like we've been in good shape there."

Biffle said the process is still being refined, and that NASCAR has allowed teams to made some adjustments to the fueling system to prevent spillage or an air lock inside the can. But it's clear that some teams are still adjusting. It's clear that the current gas can puts an even greater emphasis on precision by the pit crew and fuel man. And it's clear that filling the tank could very well have an impact on Sunday's race at Pocono, where a few drops of fuel here or there have dictated outcomes many times before.

"It could come down to fuel mileage. It could come down to a pit stop," Gordon said. "These days, as competitive as this series is, they almost all come down to the last stop."

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